Gilgamesh, The King of Heroes from Fate/Zero and Fate/Stay Night
Rau le Creuset from Gundam Seed
The Major from Hellsing Ultimate
Kotomine Kirei from Fate/Zero and Fate/Stay Night
Char Aznable, The Red Comet from many Gundam series

my favorite villanes are Hakudoshi, Kanna, Kagura and Akago out of Inuyasha and Kirea out of pretty cure and X-Dia out of shugo chara i'm not sure if she counts as a villan or not but i'll put her anyway